Updated: IPCC chief warns even two degree rise spells "bad news"

The chairman of the UN's Intergovernmental Panel on Climate Change (IPCC), Dr Rajendra K Pachauri, has today accused politicians of dragging their heels when establishing a precise definition of what constitutes "dangerous" levels of climate change, warning that even the widely accepted target of a rise in temperatures of two degrees Centigrade above pre-industrial levels would cause major disruption.

Speaking at the International Association of Research Universities (IARU) Climate Congress in Copenhagen, Pachuri said that negotiators involved in UN talks to agree to a successor to the Kyoto Treaty had repeatedly "shied away" from defining what constitutes "dangerous anthropogenic interference with the climate system".

Hinting strongly that the now widely accepted definition of "dangerous" climate of two degrees above pre-industrial levels did not go far enough, he warned that even the IPCC's best-case scenario of an increase in temperature of 1.8 degrees by 2100 was "bad news".

He warned that the IPCC's work had shown that temperature rises of between one and two degrees would result in issues with water availability, flood risk, rising sea levels and threats to human health from both an increased incidence of extreme weather events and increased disease vectors.

"Some of these factors need to be taken in... when we define what we mean by 'dangerous'," he said, adding that the impact of temperature rises would not be evenly spread with certain regions such as Bangladesh, Kolkata, Shanghai, island nations, the Mediteranean and countries bordering the North Sea facing more adverse effects than others.

Pachuri warned that to deliver even this scenario and limit temperature rises to between two and 2.4 degrees by the end of the century, carbon emissions needed to peak by 2015 at the latest in order to stabilise atmospheric concentrations of greenhouse gases at or near current levels.

He said that the clean technologies required to achieve this were already developed, but it would require a price on carbon, new incentives and levels of global investment that would result in GDP being three per cent lower than expected by 2030 – a price, he argued, that was "worth paying" to avoid even greater falls in GDP as a result of climate change.

Pachuri's comments come as Professor Katherine Richardson, chair of the IARU steering committee on climate change, warned that the latest research compiled for the conference suggested it was to limit temperature rises to two degrees.

Speaking in an interview with The Times, she said that the latest evidence suggested the world was now on track for the IPCC's worst case scenario of five to six degrees of warming.

"There is not a lot of good news, if any," she said, adding that the only hope came in the social science papers submitted to the conference, which consistently show that the economic policies and technologies needed to deliver deep cuts in emissions are already available.